Term
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Definition
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arteries-arterioles-capillaries-venules-veins
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Term
| what are the walls composed of three layer? |
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Definition
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endothelium: innermost layer, very smooth
smooth muscle: middle layer, sympathetic innervation produces vasoconstriction(lack of symp. act produces vasodilation), thickest in arteries; elastin fibers also found btwn muscle cells
collagen fibers: outer layer, also contains nerves fibers
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Term
| what are the three arteries? |
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Definition
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elastic arteries, muscular arteries, and arterioles
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Term
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Definition
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aorta & its major branches, pulmonary trunk; large diameter, elastic fibers > smooth muscle; "smooth out" or reduce fluctuation in pressure when ventricles contract not responsive to vasoconstriction(why is this important)
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Term
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Definition
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deliver blood to specific organs & muscles(carotids, brachial) elastic fibers=smooth muscle
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Term
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Definition
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small diameter
elastic fibers < smooth muscle
important in regulating blood pressure & capillary blood flow
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Term
| what are the walls of the capillaries like? |
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Definition
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walls are single layer of endothelial cells w/ small gaps btwn cells
-gas exchange & diffusion of nutrients occurs through gaps
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Term
| what's the blood-brain barrier in the capillaries? |
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Definition
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brain capilaries have no gaps so diffusion can only occur across endothelial cell membrane that forms networks called capillary beds
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Term
| what do the precapillary sphincters do in the capillaries? |
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Definition
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controls flow through capillaries, determined by tissue needs(ex: muscles, GI tract)
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Term
| what does the vascular shunt vessel do in the capillaries? |
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Definition
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directs connection of arteriole & venule, used when capillary bed in closed
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